1. Field of the Invention
This invention relates to a marine propulsion housing arrangement, and more particularly to an improved marine propulsion housing arrangement that can effectively prevent water from entering housing.
2. Description of Related Art
An outboard motor typically is mounted on a transom of an associated watercraft by means of a bracket assembly which comprises a swivel bracket and a clamping bracket. The drive unit generally includes a powering engine, a driveshaft, a propulsion device and a housing assembly. The housing assembly contains or supports the components therein. The drive unit as constructed is supported by the swivel bracket by means of mount assemblies.
FIGS. 1 and 2 illustrate an exemplary outboard motor with a conventional support structure that couples the swivel bracket to the drive unit. In particular, FIG. 1 illustrates an elevational side view of a conventional outboard motor 16 mounted on a transom 18 of an associated watercraft 20, and FIG. 2 illustrates a cross-sectional plan view taken along the line 2xe2x80x942 in FIG. 1 and showing a lower mount assembly 22 and cover members 24.
A drive unit 26 of the outboard motor 16 comprises a power head 28, a driveshaft housing 30 and a lower unit 32. The power head 28 includes an engine 34 and a protective cowling 36 encircling the engine 34. The driveshaft housing 30 depends from the power head 28 and supports a driveshaft which is driven by an output shaft of the engine 34 and extends vertically. The lower unit 32 depends from the driveshaft housing 30 and supports a propeller shaft, which is driven by the driveshaft, and a propeller 38 driven by the propeller shaft. There is a transmission mechanism including a bevel gear between the driveshaft and the propeller shaft. This transmission mechanism is shifted with a shift rod 39 so as to change a rotational direction of the propeller 38 to forward, neutral or reverse.
A swivel bracket 42 supports the drive unit 26 for pivotal movement about a generally vertically extending axis, i.e., an axis of a steering shaft 44. The steering shaft 44 passes through a shaft housing 46 of the swivel bracket 42. A clamping bracket 48 supports the swivel bracket 42 for pivotal movement about a generally extending axis, i.e., an axis of a pivot shaft 50.
An upper mount assembly 54 and the lower mount assembly 22 are provided for connecting the driveshaft housing 30 and the steering shaft 44. A steering shaft 57 is affixed to the upper mount assembly 54 and extends forwardly so that the drive unit 26 is steerable by an operator of the outboard motor 16.
The lower mount assembly 22, as shown in FIG. 2, comprises a pair of mount members 58 and a hub member 60. The respective mount members 58 are formed with inner tubes 62, outer tubes 64 and elastic bushings 66. The elastic bushings 66 are formed between the inner and outer tubes 62, 64. The hub member 60 has a boss 68 with a vertically extending bore 70. The steering shaft 44 passes through the bore 70. At both sides of the boss 68, a couple of holes 72 are provided. These holes 72 extend horizontally and fore to aft.
A front portion of the driveshaft housing 30 has a pair of recesses 73, which axes extends horizontally and fore to aft. The mount members 58 are seated in these recesses 73. A pair of bolts 74 are inserted into the inner tubes 62 of the mount members 58 and the bores 72 of the hub member 182 and then nuts 76 are placed at the other sides of the bolt heads. By tightening the bolts 74 and the nuts 76, both of the members 58, 60 are united with each other.
The lower mount assembly 22 completes with a pair of outer holders 78 that have recesses 80. The recesses 80 of outer holders 78 are then fitted onto the outer tubes 64 and fastened to the driveshaft housing 30 with bolts (not shown). Thus, the lower mount assembly 22 is affixed to the driveshaft housing 30.
The steering shaft 44 is joined with both of the upper and lower mount assemblies 54, 22 by spline connections. Accordingly, the drive unit 26 is steerable within the shaft housing 46 of the swivel bracket 42.
The pair of cover members 24 are attached onto the outer holders 78 only for concealing outer appearance of the connections that involve the mount members 58, outer holders 78 and bolts 74. These cover members cover the hub member 60. In addition, the steering shaft 44 is tubular with open upper and lower ends to allow the shift rod 39 to passes therethrough.
The associated watercraft 20 often changes its drive condition between forward and reverse. The outboard motor also is frequently trimmed up and down, and the watercraft often rises and falls as it speeds up or down or as the trim angle changes. Water surrounding the outboard motor 16 consequently can enter the steering shaft 44 from its bottom opening as shown by the arrow 82 in FIG. 1. The water, then, may go up through the steering shaft 44 and reach the power head 28. If this occurs, components such as an engine 34 within the power head 28 can be stained or salted by the water and then corrode or rust.
A need therefore exists for an improved marine propulsion housing arrangement that can inhibit water from entering a steering shaft.
In accordance with one aspect of the present invention, a marine outboard drive comprises a drive unit carrying a propulsion device. A steering shaft extends generally vertically. At least one mount assembly includes at least one mount member affixed to the drive unit and to a hub member that is united with the mount member. The hub member connects to both the drive unit and the steering shaft so as to unify the drive unit and the steering shaft. The outboard drive further comprises a swivel bracket that supports the steering shaft for pivotal movement about a steering axis. A mount cover is provided to generally cover both the mount member and the hub member.
In accordance with another aspect of the present invention, a marine outboard drive comprises a drive unit carrying a propulsion device. A tubular steering shaft has an open bottom end. At least one mount assembly is connected to both the drive unit and the steering shaft so as to couple together the drive unit and the steering shaft. The outboard drive further comprises a swivel bracket that supports the steering shaft for pivotal movement about a steering axis. A cover member covers generally encloses the bottom end of the steering shaft between the cover member and the drive unit.
Further aspects, features and advantages of this invention will become apparent from the detailed description of the preferred embodiment of the invention which follows.